Who told you that, they are non compliant with the current regulations and have been since 2015, but in the absence of other issues there is nothing compelling replacement of them
EICRs are either unsatsifactory or satsifactory (not pass/fail) [sorry, pet hate] Any C1 or C2 issues would cause an unsatsifactory outcome. In the absense of other issues, that the consumer unit is plastic would be a C3 on an escape route, and just noted with no code assigned elsewhere
The current standards allow consumer units to be non-combustable or enclosed in a fire proof enclosure, if you were trying to meet the second of these, then I know of no product that can be bought to just install over the top without removal and reinstallation, I suspect that a small cupboard built out of pink plasterboard, with a door with a fire seal would probably meet the requirements if one was so inclined